TOKYO, December 2. /TASS/. Japan’s government voiced protest over the deployment of the Russian Eastern Military District’s S-300V4 surface-to-air missile system on the Kuril Islands, the Japanese Foreign Ministry’s press service told TASS on Wednesday.

"We are constantly gathering information about the Russian military’s actions in the Northern Territories (Japan’s term to refer to Russia’s Southern Kuril Islands - TASS). On December 1, the Japanese Embassy in Russia lodged a protest with the Russian Foreign Ministry, noting that such actions can reinforce Russian military capabilities and are incompatible with our country's position on these islands," the ministry said.

On Tuesday, the Russian Defense Ministry reported that the units of the S-300V4 surface-to-air missile system of the Eastern Military District entered combat duty on the Kuril Islands.

The S-300V4 is an advanced highly mobile air defense missile system designated to protect vital military and administrative facilities and groupings of forces against strikes by ballistic and aerodynamic air attack weapons. This is the fourth version of the upgraded S-300V battlefield anti-aircraft missile system.

Russia and Japan have been in talks to sign a peace treaty since the mid-20th century. The main stumbling block to achieving this is the ownership issue over the Southern Kuril Islands, called the Northern Territories in Japan. After the end of World War II, the Kuril Islands were incorporated into the Soviet Union. However, the ownership of Iturup, Kunashir, Shikotan Islands and the Habomai Islands has been challenged by Japan. The Russian Foreign Ministry has repeatedly said that Russia’s sovereignty over these islands, which is committed to paper in international documents, cannot be called in question.